Methods and apparatus for mobility management between fixed transmission points and mobile transmission points

ABSTRACT

In a network comprising both fixed transmission points and mobile transmission points, the transmission points may transmit discovery reference signals that allow WTRUs to detect and/or synchronize to the transmission points. The fixed and mobile transmission points may transmit discovery reference signals with different characteristics that allow the WTRUs to distinguish between fixed and mobile transmission points. The mobile transmission points may also transmit a separate maintenance reference signal that allows WTRUs to maintain a connection with the mobile transmission point. For networks in which fixed a mobile transmission points operate in different frequency bands, the mobile transmission points may also periodically transmit discovery beacon signals in the frequency band of the fixed transmission points to allow discovery. Conditions may be imposed on WTRUs before the WTRU will transmit to the network a measurement report reporting on a potential transmission point to which it may be switched. Such conditions may include the speed of a WTRU relative to the transmission point with which it is currently associated, the speed of the WTRU relative to the newly discovered transmission point or both.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.16/491,416 filed Sep. 5, 2019 which is a 371 U.S. National Stage entryof PCT Application No. PCT/US2018/021835, filed Mar. 9, 2018, whichclaims the benefit of U.S. Provisional Patent Application No.62/471,720, filed on Mar. 15, 2017, the contents of which areincorporated herein fully by reference.

BACKGROUND

Mobility is one of the key differentiators between mobile wirelesssystems (e.g., LTE) and other forms of wireless communications, such asWireless LANs. In LTE, mobility control mechanisms are invoked tomaintain the quality of on-going services of User Equipment (UE or UEs)as the latter move across cells. Fundamentally, there are two kinds ofUE mobility control, namely, UE-controlled cell reselection in idle modeand network-controlled handover in connected mode. Both mobility controlmechanisms are based on the measurement of the signal strength andquality of the designated cells. One difference between the two controlmechanisms is that UEs in connected mode will be notified of thecriteria to be used for measuring and reporting purposes via theMeasurement Control messages. When any of the specified reportingcriteria are met, the UE feeds the results back to the network in aMeasurement Report message. On this basis, it is the network'sresponsibility to determine a potential handover instead of the UEperforming cell reselection in idle mode.

One desirable feature for the next-generation cellular networks, e.g.,3GPP NR (New Radio), currently under discussion is the capability tosupport a mobile transmission point (Mbl-TRP, which is typicallydeployed in a moving vehicle such as a bus, a high-speed train, anairplane, etc. In this discussion, a transmission point (TRP) generallymay belong to one of two different categories: mobile or fixed. A mobileTRP (Mbl-TRP) is a TRP that may be moving (for example, a TRP in apublic transportation vehicle, such as a bus or train), and a fixed TRP(Fxd-TRP) is a more conventional TRP such as a base station that may befixed to a geographical location. As used herein, an in-vehicle UE (orInVeh-UE) is an UE that is inside the vehicle where the Mbl-TRP ismounted, while a street-side UE (or StrSide-UE) is defined as an UEwhich is not in the vehicle (but not necessarily on the street or theside of a street).

Mbl-TRPs are primarily adapted to provide access services for InVeh-UEswhile connecting to the network (e.g. external eNBs, access points orRemote Radio Heads (RRHs) via wireless backhaul links. Therefore, aMbl-TRP can be viewed as a generalized small cell eNB with mobilityfunctionality. On one hand, due to the mobility, it is generallybeneficial for an InVeh-UEs to be connected to the Mbl-TRP instead of anexternal eNBs since the signal transmitted from the Mbl-TRP is normallythe strongest for the InVeh-UEs and therefore good performance andservice quality can be maintained. On the other hand, it can beadvantageous to prevent those UEs that are not inside the vehicle, e.g.,StrSide-UEs, from camping on or connecting to a mobile TRP to avoidpotential “ping pong” effects in cell reselection or unnecessaryhandover. As a result, it is desirable to design a robust and efficientcell reselection/handover mechanism for UEs in the scenario of mobileTRPs.

SUMMARY

In a network comprising both fixed transmission points and mobiletransmission points, the transmission points transmit discoveryreference signals that allow WTRUs to detect and/or synchronize to thetransmission points. The fixed and mobile transmission points maytransmit discovery reference signals with different characteristics thatallow the WTRUs to distinguish between fixed and mobile transmissionpoints. The mobile transmission points also transmit a separatemaintenance reference signal that allows WTRUs to maintain a connectionwith the mobile transmission point.

For networks in which fixed and mobile transmission points operate indifferent frequency bands, the mobile transmission points also mayperiodically transmit discovery beacon signals in the frequency band ofthe fixed transmission points to allow discovery.

Conditions may be imposed on WTRUs before the WTRU will transmit to thenetwork a measurement report reporting on a newly discoveredtransmission point and/or will even perform a measurement. Suchconditions may include the speed of a WTRU relative to the transmissionpoint with which it is currently associated, the speed of the WTRUrelative to the newly discovered transmission point or both.

BRIEF DESCRIPTION OF THE DRAWINGS

Furthermore, like reference numerals in the figures indicate likeelements, and wherein:

FIG. 1A is a system diagram illustrating an example communicationssystem in which one or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram illustrating an example wirelesstransmit/receive unit (WTRU) that may be used within the communicationssystem illustrated in FIG. 1A according to an embodiment;

FIG. 1C is a system diagram illustrating an example radio access network(RAN) and an example core network (CN) that may be used within thecommunications system illustrated in FIG. 1A according to an embodiment;

FIG. 1D is a system diagram illustrating a further example RAN and afurther example CN that may be used within the communications systemillustrated in FIG. 1A according to an embodiment;

FIG. 2 is a timing diagram illustrating timing of the Disc-RS andMaint-RS signals in accordance with an exemplary embodiment;

FIG. 3 is a timing diagram illustrating timing of the Disc-RS, Maint-RSand Discovery Beacon Signal in accordance with another exemplaryembodiment;

FIG. 4 is a timing diagram illustrating timing of the Disc-RS andMaint-RS in accordance with a further exemplary embodiment;

FIG. 5 is a flowchart illustrating a process for a UE to detect aMbl-TRP, determine whether to send a measurement report, and send themeasurement report in accordance with an exemplary embodiment; and

FIG. 6 is a signal flow diagram illustrating a process for UE handoverfrom a Fxd-TRP to a Mbl-TRP in accordance with an exemplary embodiment.

EXAMPLE NETWORKS FOR IMPLEMENTATION OF THE EMBODIMENTS

FIG. 1A is a diagram illustrating an example communications system 100in which one or more disclosed embodiments may be implemented. Thecommunications system 100 may be a multiple access system that providescontent, such as voice, data, video, messaging, broadcast, etc., tomultiple wireless users. The communications system 100 may enablemultiple wireless users to access such content through the sharing ofsystem resources, including wireless bandwidth. For example, thecommunications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailunique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM(UW-OFDM), resource block-filtered OFDM, filter bank multicarrier(FBMC), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a RAN104/113, a CN 106/115, a public switched telephone network (PSTN) 108,the Internet 110, and other networks 112, though it will be appreciatedthat the disclosed embodiments contemplate any number of WTRUs (alsosometimes referred to herein as User Equipment or UEs), base stations,networks, and/or network elements. Each of the WTRUs 102 a, 102 b, 102c, 102 d may be any type of device configured to operate and/orcommunicate in a wireless environment. By way of example, the WTRUs 102a, 102 b, 102 c, 102 d, any of which may be referred to as a “station”and/or a “STA”, may be configured to transmit and/or receive wirelesssignals and may include a user equipment (UE), a mobile station, a fixedor mobile subscriber unit, a subscription-based unit, a pager, acellular telephone, a personal digital assistant (PDA), a smartphone, alaptop, a netbook, a personal computer, a wireless sensor, a hotspot orMi-Fi device, an Internet of Things (IoT) device, a watch or otherwearable, a head-mounted display (HMD), a vehicle, a drone, a medicaldevice and applications (e.g., remote surgery), an industrial device andapplications (e.g., a robot and/or other wireless devices operating inan industrial and/or an automated processing chain contexts), a consumerelectronics device, a device operating on commercial and/or industrialwireless networks, and the like. Any of the WTRUs 102 a, 102 b, 102 cand 102 d may be interchangeably referred to as a UE.

The communications systems 100 may also include a base station 114 aand/or a base station 114 b. Each of the base stations 114 a, 114 b maybe any type of device configured to wirelessly interface with at leastone of the WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to oneor more communication networks, such as the CN 106/115, the Internet110, and/or the other networks 112. By way of example, the base stations114 a, 114 b may be a base transceiver station (BTS), a Node-B, an eNodeB, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller,an access point (AP), a wireless router, and the like. While the basestations 114 a, 114 b are each depicted as a single element, it will beappreciated that the base stations 114 a, 114 b may include any numberof interconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104/113, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals on one or morecarrier frequencies, which may be referred to as a cell (not shown).These frequencies may be in licensed spectrum, unlicensed spectrum, or acombination of licensed and unlicensed spectrum. A cell may providecoverage for a wireless service to a specific geographical area that maybe relatively fixed or that may change over time. The cell may furtherbe divided into cell sectors. For example, the cell associated with thebase station 114 a may be divided into three sectors. Thus, in oneembodiment, the base station 114 a may include three transceivers, i.e.,one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and mayutilize multiple transceivers for each sector of the cell. For example,beamforming may be used to transmit and/or receive signals in desiredspatial directions.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet(UV), visible light, etc.). The air interface 116 may be establishedusing any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104/113 and the WTRUs 102 a,102 b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 115/116/117 using wideband CDMA (WCDMA).WCDMA may include communication protocols such as High-Speed PacketAccess (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-SpeedDownlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access(HSUPA).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as Evolved UMTS TerrestrialRadio Access (E-UTRA), which may establish the air interface 116 usingLong Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/orLTE-Advanced Pro (LTE-A Pro).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as NR Radio Access, which mayestablish the air interface 116 using New Radio (NR).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement multiple radio access technologies. For example, thebase station 114 a and the WTRUs 102 a, 102 b, 102 c may implement LTEradio access and NR radio access together, for instance using dualconnectivity (DC) principles. Thus, the air interface utilized by WTRUs102 a, 102 b, 102 c may be characterized by multiple types of radioaccess technologies and/or transmissions sent to/from multiple types ofbase stations (e.g., a eNB and a gNB).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.11 (i.e.,Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperabilityfor Microwave Access (WiMAX)), CDMA2000, CDMA20001×, CDMA2000 EV-DO,Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), Global System for Mobile communications (GSM),Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and thelike.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, an industrialfacility, an air corridor (e.g., for use by drones), a roadway, and thelike. In one embodiment, the base station 114 b and the WTRUs 102 c, 102d may implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In an embodiment, the base station114 b and the WTRUs 102 c, 102 d may implement a radio technology suchas IEEE 802.15 to establish a wireless personal area network (WPAN). Inyet another embodiment, the base station 114 b and the WTRUs 102 c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or femtocell. Asshown in FIG. 1A, the base station 114 b may have a direct connection tothe Internet 110. Thus, the base station 114 b may not be required toaccess the Internet 110 via the CN 106/115.

The RAN 104/113 may be in communication with the CN 106/115, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. The data may have varying qualityof service (QoS) requirements, such as differing throughputrequirements, latency requirements, error tolerance requirements,reliability requirements, data throughput requirements, mobilityrequirements, and the like. The CN 106/115 may provide call control,billing services, mobile location-based services, pre-paid calling,Internet connectivity, video distribution, etc., and/or performhigh-level security functions, such as user authentication. Although notshown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or theCN 106/115 may be in direct or indirect communication with other RANsthat employ the same RAT as the RAN 104/113 or a different RAT. Forexample, in addition to being connected to the RAN 104/113, which may beutilizing a NR radio technology, the CN 106/115 may also be incommunication with another RAN (not shown) employing a GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

The CN 106/115 may also serve as a gateway for the WTRUs 102 a, 102 b,102 c, 102 d to access the PSTN 108, the Internet 110, and/or the othernetworks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) and/orthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired and/or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another CN connected to one or more RANs, whichmay employ the same RAT as the RAN 104/113 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities (e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks). For example, the WTRU 102 c shown in FIG. 1A may be configuredto communicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an example WTRU 102. As shownin FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120,a transmit/receive element 122, a speaker/microphone 124, a keypad 126,a display/touchpad 128, non-removable memory 130, removable memory 132,a power source 134, a global positioning system (GPS) chipset 136,and/or other peripherals 138, among others. It will be appreciated thatthe WTRU 102 may include any sub-combination of the foregoing elementswhile remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In an embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and/or receive both RF and light signals. It will beappreciated that the transmit/receive element 122 may be configured totransmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted in FIG. 1B as asingle element, the WTRU 102 may include any number of transmit/receiveelements 122. More specifically, the WTRU 102 may employ MIMOtechnology. Thus, in one embodiment, the WTRU 102 may include two ormore transmit/receive elements 122 (e.g., multiple antennas) fortransmitting and receiving wireless signals over the air interface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as NR and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs and/or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, a Virtual Reality and/or Augmented Reality (VR/AR) device, anactivity tracker, and the like. The peripherals 138 may include one ormore sensors, the sensors may be one or more of a gyroscope, anaccelerometer, a hall effect sensor, a magnetometer, an orientationsensor, a proximity sensor, a temperature sensor, a time sensor; ageolocation sensor; an altimeter, a light sensor, a touch sensor, amagnetometer, a barometer, a gesture sensor, a biometric sensor, and/ora humidity sensor.

The WTRU 102 may include a full duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for both the UL (e.g., for transmission) anddownlink (e.g., for reception) may be concurrent and/or simultaneous.The full duplex radio may include an interference management unit toreduce and or substantially eliminate self-interference via eitherhardware (e.g., a choke) or signal processing via a processor (e.g., aseparate processor (not shown) or via processor 118). In an embodiment,the WTRU 102 may include a half-duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for either the UL (e.g., for transmission) or thedownlink (e.g., for reception)).

FIG. 10 is a system diagram illustrating the RAN 104 and the CN 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the CN 106.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and/or receive wireless signals from, the WTRU 102a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the UL and/or DL, and the like. As shown in FIG. 10 , the eNode-Bs160 a, 160 b, 160 c may communicate with one another over an X2interface.

The CN 106 shown in FIG. 10 may include a mobility management entity(MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN)gateway (or PGW) 166. While each of the foregoing elements are depictedas part of the CN 106, it will be appreciated that any of these elementsmay be owned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the eNode-Bs 162 a, 162 b, 162 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM and/or WCDMA.

The SGW 164 may be connected to each of the eNode Bs 160 a, 160 b, 160 cin the RAN 104 via the S1 interface. The SGW 164 may generally route andforward user data packets to/from the WTRUs 102 a, 102 b, 102 c. The SGW164 may perform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when DL data is available forthe WTRUs 102 a, 102 b, 102 c, managing and storing contexts of theWTRUs 102 a, 102 b, 102 c, and the like.

The SGW 164 may be connected to the PGW 166, which may provide the WTRUs102 a, 102 b, 102 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 102 a, 102b, 102 c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may provide the WTRUs 102 a, 102 b, 102 c withaccess to circuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. For example, the CN 106 may include,or may communicate with, an IP gateway (e.g., an IP multimedia subsystem(IMS) server) that serves as an interface between the CN 106 and thePSTN 108. In addition, the CN 106 may provide the WTRUs 102 a, 102 b,102 c with access to the other networks 112, which may include otherwired and/or wireless networks that are owned and/or operated by otherservice providers.

Although the WTRU is described in FIGS. 1A-1D as a wireless terminal, itis contemplated that in certain representative embodiments that such aterminal may use (e.g., temporarily or permanently) wired communicationinterfaces with the communication network.

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an AccessPoint (AP) for the BSS and one or more stations (STAs) associated withthe AP. The AP may have an access or an interface to a DistributionSystem (DS) or another type of wired/wireless network that carriestraffic in to and/or out of the BSS. Traffic to STAs that originatesfrom outside the BSS may arrive through the AP and may be delivered tothe STAs. Traffic originating from STAs to destinations outside the BSSmay be sent to the AP to be delivered to respective destinations.Traffic between STAs within the BSS may be sent through the AP, forexample, where the source STA may send traffic to the AP and the AP maydeliver the traffic to the destination STA. The traffic between STAswithin a BSS may be considered and/or referred to as peer-to-peertraffic. The peer-to-peer traffic may be sent between (e.g., directlybetween) the source and destination STAs with a direct link setup (DLS).In certain representative embodiments, the DLS may use an 802.11e DLS oran 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS)mode may not have an AP, and the STAs (e.g., all of the STAs) within orusing the IBSS may communicate directly with each other. The IBSS modeof communication may sometimes be referred to herein as an “ad-hoc” modeof communication.

When using the 802.11ac infrastructure mode of operation or a similarmode of operations, the AP may transmit a beacon on a fixed channel,such as a primary channel. The primary channel may be a fixed width(e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling.The primary channel may be the operating channel of the BSS and may beused by the STAs to establish a connection with the AP. In certainrepresentative embodiments, Carrier Sense Multiple Access with CollisionAvoidance (CSMA/CA) may be implemented, for example in in 802.11systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, maysense the primary channel. If the primary channel is sensed/detectedand/or determined to be busy by a particular STA, the particular STA mayback off. One STA (e.g., only one station) may transmit at any giventime in a given BSS.

High Throughput (HT) STAs may use a 40 MHz wide channel forcommunication, for example, via a combination of the primary 20 MHzchannel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHzwide channel.

Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz,and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may beformed by combining contiguous 20 MHz channels. A 160 MHz channel may beformed by combining 8 contiguous 20 MHz channels, or by combining twonon-contiguous 80 MHz channels, which may be referred to as an 80+80configuration. For the 80+80 configuration, the data, after channelencoding, may be passed through a segment parser that may divide thedata into two streams. Inverse Fast Fourier Transform (IFFT) processing,and time domain processing, may be done on each stream separately. Thestreams may be mapped on to the two 80 MHz channels, and the data may betransmitted by a transmitting STA. At the receiver of the receiving STA,the above described operation for the 80+80 configuration may bereversed, and the combined data may be sent to the Medium Access Control(MAC).

Sub 1 GHz modes of operation are supported by 802.11af and 802.11ah. Thechannel operating bandwidths, and carriers, are reduced in 802.11af and802.11ah relative to those used in 802.11n, and 802.11ac. 802.11afsupports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space(TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and16 MHz bandwidths using non-TVWS spectrum. According to a representativeembodiment, 802.11ah may support Meter Type Control/Machine-TypeCommunications, such as MTC devices in a macro coverage area. MTCdevices may have certain capabilities, for example, limited capabilitiesincluding support for (e.g., only support for) certain and/or limitedbandwidths. The MTC devices may include a battery with a battery lifeabove a threshold (e.g., to maintain a very long battery life).

WLAN systems, which may support multiple channels, and channelbandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include achannel which may be designated as the primary channel. The primarychannel may have a bandwidth equal to the largest common operatingbandwidth supported by all STAs in the BSS. The bandwidth of the primarychannel may be set and/or limited by a STA, from among all STAs inoperating in a BSS, which supports the smallest bandwidth operatingmode. In the example of 802.11ah, the primary channel may be 1 MHz widefor STAs (e.g., MTC type devices) that support (e.g., only support) a 1MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.Carrier sensing and/or Network Allocation Vector (NAV) settings maydepend on the status of the primary channel. If the primary channel isbusy, for example, due to a STA (which supports only a 1 MHz operatingmode), transmitting to the AP, the entire available frequency bands maybe considered busy even though a majority of the frequency bands remainsidle and may be available.

In the United States, the available frequency bands, which may be usedby 802.11ah, are from 902 MHz to 928 MHz. In Korea, the availablefrequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the availablefrequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidthavailable for 802.11ah is 6 MHz to 26 MHz depending on the country code.

FIG. 1D is a system diagram illustrating the RAN 113 and the CN 115according to an embodiment. As noted above, the RAN 113 may employ an NRradio technology to communicate with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The RAN 113 may also be in communication with theCN 115.

The RAN 113 may include gNBs 180 a, 180 b, 180 c, though it will beappreciated that the RAN 113 may include any number of gNBs whileremaining consistent with an embodiment. The gNBs 180 a, 180 b, 180 cmay each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the gNBs 180 a, 180 b, 180 c may implement MIMO technology. For example,gNBs 180 a, 180 b may utilize beamforming to transmit signals to and/orreceive signals from the gNBs 180 a, 180 b, 180 c. Thus, the gNB 180 a,for example, may use multiple antennas to transmit wireless signals to,and/or receive wireless signals from, the WTRU 102 a. In an embodiment,the gNBs 180 a, 180 b, 180 c may implement carrier aggregationtechnology. For example, the gNB 180 a may transmit multiple componentcarriers to the WTRU 102 a (not shown). A subset of these componentcarriers may be on unlicensed spectrum while the remaining componentcarriers may be on licensed spectrum. In an embodiment, the gNBs 180 a,180 b, 180 c may implement Coordinated Multi-Point (CoMP) technology.For example, WTRU 102 a may receive coordinated transmissions from gNB180 a and gNB 180 b (and/or gNB 180 c).

The WTRUs 102 a, 102 b, 102 c may communicate with gNBs 180 a, 180 b,180 c using transmissions associated with a scalable numerology. Forexample, the OFDM symbol spacing and/or OFDM subcarrier spacing may varyfor different transmissions, different cells, and/or different portionsof the wireless transmission spectrum. The WTRUs 102 a, 102 b, 102 c maycommunicate with gNBs 180 a, 180 b, 180 c using subframe or transmissiontime intervals (TTIs) of various or scalable lengths (e.g., containingvarying number of OFDM symbols and/or lasting varying lengths ofabsolute time).

The gNBs 180 a, 180 b, 180 c may be configured to communicate with theWTRUs 102 a, 102 b, 102 c in a standalone configuration and/or anon-standalone configuration. In the standalone configuration, WTRUs 102a, 102 b, 102 c may communicate with gNBs 180 a, 180 b, 180 c withoutalso accessing other RANs (e.g., such as eNode-Bs 160 a, 160 b, 160 c).In the standalone configuration, WTRUs 102 a, 102 b, 102 c may utilizeone or more of gNBs 180 a, 180 b, 180 c as a mobility anchor point. Inthe standalone configuration, WTRUs 102 a, 102 b, 102 c may communicatewith gNBs 180 a, 180 b, 180 c using signals in an unlicensed band. In anon-standalone configuration WTRUs 102 a, 102 b, 102 c may communicatewith/connect to gNBs 180 a, 180 b, 180 c while also communicatingwith/connecting to another RAN such as eNode-Bs 160 a, 160 b, 160 c. Forexample, WTRUs 102 a, 102 b, 102 c may implement DC principles tocommunicate with one or more gNBs 180 a, 180 b, 180 c and one or moreeNode-Bs 160 a, 160 b, 160 c substantially simultaneously. In thenon-standalone configuration, eNode-Bs 160 a, 160 b, 160 c may serve asa mobility anchor for WTRUs 102 a, 102 b, 102 c and gNBs 180 a, 180 b,180 c may provide additional coverage and/or throughput for servicingWTRUs 102 a, 102 b, 102 c.

Each of the gNBs 180 a, 180 b, 180 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, scheduling of users in the ULand/or DL, support of network slicing, dual connectivity, interworkingbetween NR and E-UTRA, routing of user plane data towards User PlaneFunction (UPF) 184 a, 184 b, routing of control plane informationtowards Access and Mobility Management Function (AMF) 182 a, 182 b andthe like. As shown in FIG. 1D, the gNBs 180 a, 180 b, 180 c maycommunicate with one another over an Xn interface.

The CN 115 shown in FIG. 1D may include at least one AMF 182 a, 182 b,at least one UPF 184 a,184 b, at least one Session Management Function(SMF) 183 a, 183 b, and possibly a Data Network (DN) 185 a, 185 b. Whileeach of the foregoing elements are depicted as part of the CN 115, itwill be appreciated that any of these elements may be owned and/oroperated by an entity other than the CN operator.

The AMF 182 a, 182 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N2 interface and may serve as acontrol node. For example, the AMF 182 a, 182 b may be responsible forauthenticating users of the WTRUs 102 a, 102 b, 102 c, support fornetwork slicing (e.g., handling of different PDU sessions with differentrequirements), selecting a particular SMF 183 a, 183 b, management ofthe registration area, termination of NAS signaling, mobilitymanagement, and the like. Network slicing may be used by the AMF 182 a,182 b in order to customize CN support for WTRUs 102 a, 102 b, 102 cbased on the types of services being utilized WTRUs 102 a, 102 b, 102 c.For example, different network slices may be established for differentuse cases such as services relying on ultra-reliable low latency (URLLC)access, services relying on enhanced massive mobile broadband (eMBB)access, services for machine type communication (MTC) access, and/or thelike. The AMF 162 may provide a control plane function for switchingbetween the RAN 113 and other RANs (not shown) that employ other radiotechnologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP accesstechnologies such as WiFi.

The SMF 183 a, 183 b may be connected to an AMF 182 a, 182 b in the CN115 via an N11 interface. The SMF 183 a, 183 b may also be connected toa UPF 184 a, 184 b in the CN 115 via an N4 interface. The SMF 183 a, 183b may select and control the UPF 184 a, 184 b and configure the routingof traffic through the UPF 184 a, 184 b. The SMF 183 a, 183 b mayperform other functions, such as managing and allocating UE IP address,managing PDU sessions, controlling policy enforcement and QoS, providingdownlink data notifications, and the like. A PDU session type may beIP-based, non-IP based, Ethernet-based, and the like.

The UPF 184 a, 184 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N3 interface, which may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between the WTRUs 102a, 102 b, 102 c and IP-enabled devices. The UPF 184, 184 b may performother functions, such as routing and forwarding packets, enforcing userplane policies, supporting multi-homed PDU sessions, handling user planeQoS, buffering downlink packets, providing mobility anchoring, and thelike.

The CN 115 may facilitate communications with other networks. Forexample, the CN 115 may include, or may communicate with, an IP gateway(e.g., an IP multimedia subsystem (IMS) server) that serves as aninterface between the CN 115 and the PSTN 108. In addition, the CN 115may provide the WTRUs 102 a, 102 b, 102 c with access to the othernetworks 112, which may include other wired and/or wireless networksthat are owned and/or operated by other service providers. In oneembodiment, the WTRUs 102 a, 102 b, 102 c may be connected to a localData Network (DN) 185 a, 185 b through the UPF 184 a, 184 b via the N3interface to the UPF 184 a, 184 b and an N6 interface between the UPF184 a, 184 b and the DN 185 a, 185 b.

In view of FIGS. 1A-1D, and the corresponding description of FIGS.1A-1D, one or more, or all, of the functions described herein withregard to one or more of: WTRU 102 a-d, Base Station 114 a-b, eNode-B160 a-c, MME 162, SGW 164, PGW 166, gNB 180 a-c, AMF 182 a-b, UPF 184a-b, SMF 183 a-b, DN 185 a-b, and/or any other device(s) describedherein, may be performed by one or more emulation devices (not shown).The emulation devices may be one or more devices configured to emulateone or more, or all, of the functions described herein. For example, theemulation devices may be used to test other devices and/or to simulatenetwork and/or WTRU functions.

The emulation devices may be designed to implement one or more tests ofother devices in a lab environment and/or in an operator networkenvironment. For example, the one or more emulation devices may performthe one or more, or all, functions while being fully or partiallyimplemented and/or deployed as part of a wired and/or wirelesscommunication network in order to test other devices within thecommunication network. The one or more emulation devices may perform theone or more, or all, functions while being temporarilyimplemented/deployed as part of a wired and/or wireless communicationnetwork. The emulation device may be directly coupled to another devicefor purposes of testing and/or may performing testing using over-the-airwireless communications.

The one or more emulation devices may perform the one or more, includingall, functions while not being implemented/deployed as part of a wiredand/or wireless communication network. For example, the emulationdevices may be utilized in a testing scenario in a testing laboratoryand/or a non-deployed (e.g., testing) wired and/or wirelesscommunication network in order to implement testing of one or morecomponents. The one or more emulation devices may be test equipment.Direct RF coupling and/or wireless communications via RF circuitry(e.g., which may include one or more antennas) may be used by theemulation devices to transmit and/or receive data.

DETAILED DESCRIPTION I. Overview and Terminology

A major issue in networks with Mbl-TRPs is to ensure that both InVeh-UEsand StrSide-UEs are connected to the proper cell in order to maintain agood quality-of-service and to avoid unnecessary signaling overhead andpotential service drop due to improper handover. Similar to aheterogeneous network (HetNet) deployment, a Mbl-TRP can be configuredas either in-band (same frequency band as the overlay macro-cell eNB) orout-of-band (different frequency band from the overlay macro-cell eNB).When Mbl-TRPs are introduced into a network, traditional mobilitycontrol mechanisms, for instance, as used in LTE, may have issues, atleast some of which are detailed as follows.

First, in some Mbl-TRP scenarios, the traditional mobility control maycause inappropriate handover decisions. For InVeh-UEs, for example, thiscan happen when the vehicle moves close to an external eNB whoseReference Signal Received Power (RSRP) has become stronger than that ofthe Mbl-TRP due to a large transmission power differential between theexternal eNB and the Mbl-TRP. This may trigger measurement reportingevents, which may lead to the InVeh-UEs being “wrongly” handed over tothe external eNB by the network. As the vehicle moves away from theexternal eNB, the InVeh-UEs may subsequently be handed over back to theMbl-TRP, leading to the so-called “ping-pong” effect. Meanwhile, sucheffect can also occur for StrSide-UEs, for example, when a vehiclecarrying a Mbl-TRP stops at some location close to the StrSide-UEs. Inthis scenario, it is advantageous to prevent the StrSide-UEs fromhanding over to the Mbl-TRP in order to avoid the potential unnecessaryhandover and ping ponging. In addition, allowing StrSide-UEs to camp onthe Mbl-TRP may cause a capacity issue as the Mbl-TRP may have a limitedcapacity dimensioned to the maximum number of InVeh-UEs.

Second, in traditional mobility control schemes, UEs in either idle orconnected mode need to continually measure the RSRP of a list of cells.A negative effect of such continuous measuring in a network withMbl-TRPs is the potential for excessive signaling overhead associatedwith reporting by a large number of InVeh-UEs, which may further causeradio signaling congestion. In general, InVeh-UEs are normally expectedto be camped on or connected to a Mbl-TRP rather than an external eNBdue to the lower path loss. Ideally, there is no need for InVeh-UEs toreport the measurements from static eNBs or other Mbl-TRPs whenconnected to the Mbl-TRP.

Third, out-of-band Mbl-TRPs may also be configured in some scenarios foroptimizing the network planning. In this case, for mobility from anexternal eNB to the Mbl-TRP, StrSide-UEs need first to discover theMbl-TRP through inter-frequency measurements. Inter-frequencymeasurements usually rely on the use of periodic (or non-periodic),gap-assisted measurements, which inherently would interrupt the DL/ULtransmission (unless the UEs are equipped with more than one receiver).To avoid too many interruption or unnecessary measurements, conditionsto trigger inter-frequency measurement of a possible Mbl-TRP should becarefully designed.

II. Mbl-TRP Discovery

In this section, embodiments to enable a UE to determine whether thesource of a signal is a Fxd-TRP (e.g., a conventional base station) or amobile transmission point (Mbl-TRP) are provided.

Two Types of Synchronization Signals are Transmitted by Mbl-TRPs: Onefor Mbl-TRP Discovery and One for Maintenance

In a first example embodiment, the Mbl-TRP may be configured to transmittwo types of synchronization signals, namely, a discovery referencesignal (Disc-RS) and a maintenance reference signal (Maint-RS). Thisconcept is illustrated in FIG. 2 .

The Disc-RS and Maint-RS may be transmitted periodically, potentiallywith different periodicity and time offset values. For example asillustrated in FIG. 2 , the Disc-RS is transmitted with a periodicity ofTd (in this example Td equals 80 ms) while the Maint-RS is transmittedwith a periodicity of Tm (in this example Tm equals 40 ms). Both Td andTm may be fixed in the specifications or may be configurable by thenetwork. Optionally, they may take the different values based on theperformance requirements for cell acquisition and maintenance.

In general, the Disc-RS may be used by a UE in either idle or connectedmodes for normal LTE operations. For example, the Disc-RS may be usedfor cell identification and synchronization for subsequent cellselection/reselection by UEs in idle mode and for cell measurement byUEs in connected mode. One specific example of the Disc-RS may be thecombination of PSS/SSS (Primary Synchronization Signal/SecondarySynchronization Signal) and the Cell-Specific Reference Signal (CRS)defined in LTE, where the PSS/SSS may be used for cell identificationand frame level and symbol level synchronization. The quality of thecell may be measured on the CRS.

The Disc-RS may be configured with different characteristics for UEs indifferent modes, for example, different periodicity and/or signal type.One example may be the small cell discovery reference signal defined inLTE R12 for small cell enhancement. For a small cell in ON status, theDisc-RS may be the PSS/SSS and CRS for normal LTE operations. For asmall cell in OFF status, the Disc-RS may be the small cell discoveryreference signal. The latter may be a combination of PSS/SSS, CRS, andChannel State Information Reference Signal (CSI-RS), which may be usedfor cell discovery and measurement for UE in connected mode only duringthe Disc-RS Occasions. Another example of Disc-RS may be the NR PSS/SSSand the Mobility Reference signal (MRS) in NR. To be more specific, a UEin idle mode may monitor the NR PSS/SSS less often while a UE inconnected mode may monitor the MRS more often.

The Maint-RS, on the other hand, may be used by a UE in connected mode,or more generally when associated with (e.g., camped in idle mode) theMbl-TRP, for maintaining connection to the Mbl-TRP and for measuring thesignal quality of the Mbl-TRP. Similar to the Disc-RS, the Maint-RS mayalso be configured to be different depending on whether the UEsconnected to it are in idle mode or connected mode. For example, theMaint-RS may be configured to be transmitted more frequently if theMbl-TRP is active for at least one connected UE. On the other hand, theMbl-TRP may be configured to transmit the Maint-RS less frequently whenonly UEs in idle-mode are associated with the Mbl-TRP.

Disc-RS is Received by the UE to Determine the Presence of a Mbl-TRPBased on Signature Sequence Characteristics

The UE in idle mode may use the Disc-RS, for example, for cell initialaccess, symbol and frame level synchronization, and/or cellidentification. In one specific example, in which the Disc-RS is thePSS/SSS in an LTE system, PSS and SSS may be used for symbol level andframe level synchronizations and also for cell identification. A UEcurrently connected to a Fxd-TRP may also use the Disc-RS, for example,for Mbl-TRP detection, Mbl-TRP cell synchronization, and/or cellmeasurement purposes.

In a first set of approaches, UEs may be configured to differentiate aMbl-TRP from a Fxd-TRP based on the characteristics of at least one ofthe received synchronization signals. For example, a first set ofsignature sequence characteristics may be used for Fxd-TRPs and a secondset of signature sequences characteristics may be used for Mbl-TRPs. TheUE may receive a synchronization signal and determine thecharacteristics of the signature sequence. Based on thosecharacteristics, the UE may then determine the category of the TRP(Mbl-TRP or Fxd-TRP).

More specifically, the UE may use one or more of the following signalcharacteristics to determine the TRP category:

-   -   Time (e.g., time offset relative to frame timing, periodicity,        etc.);    -   Set of Physical Resource Blocks (PRBs) over which it is        transmitted (or frequency);    -   Beam, or beam parameter. For example, a Fxd-TRP may transmit a        synchronization signal using a wide beam, whereas a Mbl-TRP may        transmit a synchronization signal using a narrow-beam. A UE may        distinguish between a wide beam transmission and a swept narrow        beam transmission, for instance, by detecting time dependent        aspects of a swept beam, such as cyclical timing aspects and/or        cyclical signal strength aspects. Alternatively, the UE may        distinguish between a wide beam transmission and a swept narrow        beam transmission based on the channel characteristics, e.g.,        the maximum delay spread of multipath channel experienced by the        signals. The multipath channel associated with a narrow beam        transmission may have smaller maximum delay spread than that        associated with a wide beam transmission;    -   Synchronization signal block (SS block) used to transmit the        synchronization signal;    -   Signal sequence type (e.g. Zadoff-Chu, Gold, Kasami, etc.);        and/or    -   Sequence parameter (e.g., for Zadoff-Chu, a different root        and/or cyclic shift can be used).

In another embodiment, a UE may first detect the presence of a Disc-RSand, from such, may determine the presence of a TRP (which, at first,could be either a Mbl-TRP or a Fxd-TRP depending on whether or not aMaint-RS associated with the Disc-RS is further detected). The UE maythen attempt to detect a Maint-RS associated with the Disc-RS in orderto determine whether it is a Mbl-TRP or a Fxd-TRP. In order to determinewhether the TRP is a Mbl-TRP or a Fxd-TRP, for example, a Maint-RSdetection timer may be started upon detection of the Disc-RS. Uponsuccessful detection of a Maint-RS associated with the Disc-RS (e.g.,before expiration of the Maint-RS detection timer), the UE may determinethat it has detected a Mbl-TRP. If no associated Maint-RS is detectedbefore the Maint-RS detection timer expires, the UE may determine thatit has detected a Fxd-TRP. One potential benefit of this embodiment isthat the Mbl-TRP and the Fxd-TRP may reuse the same signal sequence typeand sequence parameters, thus preventing excessive use of the limitednumber of unique sequences.

A Maint-RS may be considered to be associated with a Disc-RS if at leastone of its signal characteristics is determined from at least one signalcharacteristic of the Disc-RS. For instance, the UE may use at least oneof the following to enable detection of a Maint-RS associated with apreviously detected Disc-RS:

-   -   Time. For example, there may be a specific time offset (or set        of time offsets) between a Disc-RS and a Maint-RS associated        with a single Mbl-TRP. For example, a Disc-RS received in symbol        n of subframe k may be associated with a set of Maint-RS        transmitted in symbol m=n+i or subframes k+x, k+y, k+z;    -   Frequency. For example, there may be a predetermined frequency        offset between a Disc-RS and a Maint-RS associated with the same        Mbl-TRP;    -   Beam or beam parameter. For example, a beam used to transmit a        Disc-RS may indicate a possible beam used for Maint-RS;    -   Signal sequence type (e.g. Zadoff-Chu, Gold, Kasami, etc.);        and/or    -   Sequence parameter (e.g. for Zadoff-Chu, root, cyclic shift).        For example, a sequence parameter of a Disc-RS may indicate a        transmission parameter of a Maint-RS from the same Mbl-TRP.

In yet another embodiment, the MBL-TRP may be configured so as to nottransmit a Maint-RS when there are no WTRU's associated with it (e.g.,in order to conserve power and/or radio resources). In such embodiments,upon detection of the presence of a Disc-RS, a UE may initiate an ULtransmission to trigger the Mbl-TRP to start transmitting a Maint-RS.

Maint-RS is Received by the UE to Maintain the Connection to the Mbl-TRP

A UE in connected mode, or more generally, associated with (e.g., campedin Idle mode) a Mbl-TRP, may use the Maint-RS, for example, formaintaining connection to the Mbl-TRP and for measuring the signalquality of the Mbl-TRP. In a first set of embodiments, the Maint-RS maybe configured with different characteristics from those of the Disc-RS.For example, the Maint-RS and the Disc-RS may be transmitted usingdifferent timing offsets relative to the frame timing and/or usingdifferent periodicities. The UE associated with the Mbl-TRP may receivethe Maint-RS and detect its corresponding characteristics, based onwhich, the UE may measure the strength and quality of the Mbl-TRP andmaintain connection to the Mbl-TRP.

To be more specific, the UE may use one or more of the following signalcharacteristics to identify the Maint-RS and differentiate the Maint-RSfrom the Disc-RS:

-   -   Time (e.g., offset relative to frame timing, periodicity, etc.);    -   Set of PRBs over which it is transmitted (or frequency);    -   Beam or beam parameter. For example, a Disc-RS may be        transmitted using beam sweeping and may thus be transmitted over        a plurality of beams whereas a Maint-RS may be transmitted using        a subset of beams (e.g. a single beam);    -   Synchronization signal block (SS block);    -   Signal sequence type (e.g., Zadoff-Chu, Gold, Kasami, etc.);        and/or    -   Sequence parameter (e.g. root sequence and cyclic shift for a        Zadoff-Chu sequence).

Maint-RS Signal is Possibly Superimposed on Data to Reduce ResourceOverhead

In another embodiment, the Maint-RS may use the same time and frequencyresources as the downlink payload data. Specifically, the Maint-RS maybe superimposed onto the downlink payload data using the same time andfrequency resources and be separable from the downlink payload data bythe receiver because of the known signal characteristics of theMaint-RS. The UE may monitor certain time and frequency resources knownto be potentjally occupied by both downlink payload data and theMaint-RS, and detect the Maint-RS based on the characteristics of theMaint-RS. More specifically, the UE may rely on one or more of thefollowing characteristics to detect the Maint-RS:

-   -   Low transmission power of the Maint-RS to minimize the        interference towards the downlink payload data; and/or    -   Long signature sequence to achieve high processing gain to        detect the Maint-RS from the downlink payload data.

The benefit of this approach is that the Maint-RS may be transmittedwithout dedicated resources. In practice, depending on the design, itmay also imply that the UE may require an advanced receiver architecture(e.g., successive interference cancellation based receiver) in order todetect the data.

Discovery Signal is Received by the UE to Determine the Presence of aMbl-TRP Operating on a Different Frequency

In yet another embodiment, the Mbl-TRP may be configured in theout-of-band mode, i.e., the Mbl-TRPs operate in a frequency or carrierdifferent from the Fxd-TRPs in the network. In this scenario, theMbl-TRPs may be configured to also transmit a discovery beacon signal onthe Fxd-TRP frequency. This concept is illustrated in FIG. 3 .

The discovery beacon signal may be transmitted periodically withconfigurable periodicity and time offset values. As an illustrativeexample, in FIG. 3 , the discovery beacon signal is transmitted with aperiodicity of Tb=40 ms.

In one option, the discovery beacon signal may be designed using asimilar structure to the Maint-RS and/or Disc-RS as described above. Inanother option, some existing mechanisms such as small cell discoverymay be used for this purpose. For example, the UE in either idle mode orwhen connected to the Fxd-TRP may monitor the discovery beacon signal,for example, for Mbl-TRP discovery. One specific example of thediscovery beacon signal may be the Device-to-Device (D2D)-type discoverysignal used in LTE D2D proximity services. See, e.g., 3GPP TS 36.300v12.10.0, § 23.11.

Another approach is to use the small cells discovery approach. A UE maybe configured with time instances (or occasions) where it may attempt todetect the discovery beacon signal. Upon detection of a discovery beaconsignal and other criteria for inter-frequency measurement as discussedbelow, the UE may use a pre-configured and/or associated measurement gapto attempt to detect the Disc-RS/Maint-RS of the Mbl-TRP in itsappropriate frequency. Alternatively, upon detecting a discovery beaconsignal, the UE may indicate to its serving TRP the need for ameasurement gap to attempt detection of Mbl-TRPs.

To detect the presence of the Mbl-TRP, in the first set of embodiments,the UE may be configured to identify the discovery beacon signal basedon the characteristics of the received discovery signal, such as in wayssimilar to any of the ways described above in connection with detectingthe Maint-RS.

UE Uses Inter-RAT Signals/Messages to Detect Presence of a Mbl-TRP

In yet another embodiment, the UEs may exploit one or more of thefollowing forms of inter-RAT signals or messages to detect the presenceof a Mbl-TRP in out-of-band mode:

-   -   Wi-Fi and Bluetooth signals transmitted from the access points        installed in the same vehicle in which the Mbl-TRP is installed;        and/or    -   Vehicular safety messages periodically transmitted by the        vehicles, which may include the vehicle ID, location, speed, and        heading information. One specific example of the safety messages        may be the V2V/V2P messages transmitted by the vehicle using        DSRC or other V2x technology such as what is defined in LTE        Release 14 for Vehicle-to-Vehicle (V2V) services. See, e.g.,        3GPP TS 22.185, V14.2.1 § 4.1.2.

More specifically, the UE may be configured to monitor and/or receiveone or more of the above inter-RAT signals/messages. For example, the UEmay be configured by the mobile operator network (e.g., via the cellularlink) or pre-configured (e.g., via its UICC or other pre-configurationmethods) with the inter-RAT parameters to consider. The UE may furtherbe configured by the network to enable this inter-RAT discovery.

III. Conditions to Trigger Measurement Report in the Presence of Mbl-TRP

This section discusses embodiments for a UE to determine when to send ameasurement report to the network. For a possible handover from aFxd-TRP to a Mbl-TRP or from a Mbl-TRP to a Fxd-TRP, the UE may beconfigured with at least one of the following criteria for reportingmeasurement data:

-   -   The RSRP or the like (e.g., received power measurement on a        subset of resources) of the Mbl-TRP becomes better than a        pre-configured threshold;    -   The RSRP or the like (e.g. received power measurement on a        subset of resources) of the Fxd-TRP becomes worse than a        pre-configured threshold;    -   Multiple RSRP measurements or the like (e.g. received power        measurement on a subset of resources) of the Mbl-TRP indicate        stability with respect to the channel between the Mbl-TRP and        the UE (for example, a UE may perform a set of x RSRP        measurements at different, possibly configurable, time        instances; and, upon determining that at least y (where y<=x)        measurements are within a threshold value of each other, the UE        may be triggered to report the set of measurements, and/or the        average measurement, and/or the number of measurements y that        fall within a threshold value of the reported measurement);    -   The UE's speed relative to the Mbl-TRP is below another        pre-configured threshold, i.e., indicative of a likelihood that        the UE is an InVeh-UE with the Mbl-TRP;    -   The UE's speed relative to the Mbl-TRP is greater than a        pre-configured threshold, i.e., indicative of a likelihood that        the UE is mobile but is not in the same vehicle as the Mbl-TRP;        and/or    -   The UE's speed relative to the Mbl-TRP fluctuates by a value        greater than a threshold, i.e., indicative of a likelihood that        the UE is mobile but is not in the same vehicle as the Mbl-TRP        (for example, a UE may determine its speed relative to the        Mbl-TRP at multiple, say x, occasions, and, if y such        measurements (where y<=x) vary by an amount greater than a        threshold value from some normalized value, the UE may consider        a measurement reporting criteria to have been achieved.

Examples of such normalized values may include:

-   -   a specific relative speed measurement taken on a possibly        configurable occasion;    -   the average relative speed measurement taken over a set of        occasions; and/or    -   a maximum or minimum relative speed measurement taken in one of        the x measurement occasions.

In one embodiment, the UE may be configured with a first subset ofconditions, which may be one or more of the above conditions, toinitiate further consideration of whether to trigger a measurementreport. Specifically, the UE may then be configured with a second subsetof conditions, which may be one or more of the above conditions. The UEmay be configured to trigger the reporting events only if both of thetwo subsets of conditions are met. For example, the UE may be configuredwith the first condition being that the UE's relative speed to theMbl-TRP is below a pre-configured threshold. Upon the satisfaction ofthe first condition, the UE may determine whether a second subset ofconditions are met. As a more specific example, the second subset ofconditions may be that the RSRP of the Mbl-TRP becomes better than apre-configured threshold and/or the RSRP of the Fxd-TRP becomes worsethan a pre-configured threshold.

The UE may report measurements for one (or more) Mbl-TRP along with one(or more) Fxd-TRP. In an embodiment, when a UE is triggered to reportmeasurements for a Mbl-TRP, the UE may also report all valid Fxd-TRPmeasurements, regardless of whether those measurements satisfy their ownindividual reporting criteria. The thresholds for reporting Mbl-TRP orFxd-TRP measurements may be different depending on whether the TRP beingmeasured is a Mbl-TRP or a Fxd-TRP. Furthermore, the thresholds forreporting Mbl-TRP or Fxd-TRP measurements may depend on the TRP typethat the UE is currently served by (e.g., whether the UE is an InVeh-UEor an StrSide-UE).

UE is Configured with a Criterion Based on Relative Speed Estimation

As noted above, the UE may determine whether to send a measurementreport based at least partially on a relative speed measurement (orspeed estimate) and one or more configured thresholds.

For example, once the UE detects the Disc-RS transmitted by a Mbl-TRP,the UE may be configured to estimate its speed relative to the Mbl-TRP.The UE may estimate its speed, for example, based on estimating thechannel coherence time using the signal characteristics of the receivedreference signals in a similar way as described below in connection withthe section of this specification concerning condition for a UE to sendan inter-frequency measurement request, or based on multiple consecutiveRSRP measurements of the Mbl-TRP, which indicate stability with respectto the channel between the UE and the Mbl-TRP. Based on the estimatedrelative speed, the UE may further categorize the speed level. Forexample, the UE may decide whether the relative speed is “low” or “high”based on one or more configured thresholds.

In this context, the UE may be in one of four scenarios, which aresummarized in Table 1.

TABLE 1 Speed level relative to Mbl- TRP Low High Scenario 1) UE is“InVeh-UE” 1) UE is on a different vehicle than the Mbl-TRP and movingin a different direction and/or at a different speed. 2) UE is“StrSide-UE” and 2) UE is “StrSide-UE”, and Mbl-TRP stopped closeMbl-TRP is moving. to the UE (e.g. Mbl-TRP is in a vehicle that isstopped at a bus stop or a red light)

In one embodiment, the UE may be configured to trigger measurementreporting if, as a first condition, the UE's estimated speed levelrelative to the Mbl-TRP is below a pre-configured threshold, i.e., therelative speed level is “low”, and a second subset of one or moreconditions is met. In this case, the UE may be classified as an InVeh-UEaccording to Table 1. Therefore, it may be beneficial to consider apossible handover to the Mbl-TRP due to the low path loss between theMbl-TRP and the UEs in the cabin and/or because the InVeh-UE's positionmay be fixed relative to the Mbl-TRP, and thus it is reasonable toassume that the two are moving together, i.e., that the UE is an“InVeh-UE” relative to that Mbl-TRP. On the other hand, if the UE'sspeed relative to the Mbl-TRP is “high”, then it may be reasonable toassume that the UE is not in the Mbl-TRP vehicle, and thus the UE may beconfigured to not send the measurement report (i.e., conceptually, theUE “ignores” the Mbl-TRP and stays connected the Fxd-TRP).

Estimation of Level of Relative Speed Based on Radio Measurements

The level of the UE's speed relative to the Mbl-TRP may be estimatedfrom a higher layer based on radio measurements, e.g., RSRP or the likebased on Disc-RS, CRS or other forms of reference signals transmitted bythe Mbl-TRP. The UE may determine its relative speed using multipleradio measurements in a pre-configured time frame. In one approach, theUE measures the fluctuations of the measured RSRP over time and comparesthem with a threshold (e.g., a small threshold). If a certain percentageof such measurements (e.g., half of the measurements) are within apredetermined range of each other, the UE may consider its speedrelative to the Mbl-TRP to be low. Otherwise, it may consider its speedrelative to the Mbl-TRP to be high.

In another approach, the UE may use statistics of multiple measuredRSRPs or the like, for example, the second-order moment, to determinethe level of relative speed. If the measured second-order moment issmall, then the UE considers its relative speed low and vice versa.

Estimation of Level of Relative Speed Based on V2X Messages

In yet other embodiments, the UE's relative speed with respect to aMbl-TRP may be estimated based on received Vehicle to-Vehicle orVehicle-to-Infrastructure (V2X) messages. Specifically, the UE mayreceive V2X messages transmitted (either periodically orevent-triggered) by the vehicle carrying the Mbl-TRP. The V2X messagesmay contain the identification of the vehicle and the Mbl-TRP, speed,direction and location of the vehicle. In one embodiment, the UE mayobtain its own absolute speed and direction using higher layerapplications, such as GPS. The UE would then compare its speed and/ordirection to the speed and/or direction reported in the V2X message(s)in order to make a determination as to its speed and/or directionrelative to the Mbl-TRP's.

In another embodiment, the UE may obtain its speed and/or directionusing network-assisted location determination methods. For example, theUE may measure the time-of-arrival (TOA) of reference signalstransmitted by multiple Fxd-TRPs within the NR network and subsequentlythe UE may estimate its speed and direction using location measurementson different time occasions.

Determination of Different Thresholds Associated with MeasurementReporting Conditions

The UE's estimate of radio link quality of the serving or target cellsin terms of RSRP or the like may be compared to one or more configurablethresholds for purposes of determining whether or not to send ameasurement report. In one approach, the threshold may be determinedbased on hypothetical or real transmission of the reference signals,e.g., through simulation/field test. The threshold may be set to a valuethat guarantees a certain level of probability of detection of thereference signals, e.g., 99%. An offset may be added to the threshold toaccount for factors in practical scenarios, such as interference,small-scale fading, receiver noise, and so on.

Additionally, the UE's relative speed estimate may be compared toanother configurable threshold for purposes of determining whether ornot to send a measurement report. One approach is to set the thresholdto be a small number, e.g., around 3-5 km/h, to ensure that the UE isessentially travelling inside the vehicle while also considering thatthe UE may walk in the vehicle, e.g., in a train.

The UE may be configured with the thresholds via Radio Resource Control(RRC) signaling, for example, when setting up the measurements, or thethresholds may be fixed in the specifications.

Mbl-TRP Uses Speed-Dependent Disc-RS Activation to Avoid UnnecessaryHandover

One potential issue with the above-described relative speed-basedembodiment is that a UE may determine that its relative speed is “low”yet still be an StrSide-UE (the scenario in the lower left quadrant ofTable 1). This may happen, for example, when the Mbl-TRP vehicle stopsor moves slowly on the street while close to an StrSide-UE. In thiscase, sending a measurement report may not be beneficial for the UE asit is not an InVeh-UE and thus it may cause unnecessary signaling,possibly unneeded handover, and possibly undesirable “ping-pong” effect.Thus, as noted above, there may be an ambiguity if the UE relies only onthe estimation of the relative speed with respect to the Mbl-TRP.

In one exemplary embodiment adapted to address this scenario, theMbl-TRP may be configured to transmit its Disc-RS as a function of theMbl-TRP's speed, a concept referred to herein as “speed-dependentDisc-RS activation”. More specifically, the Mbl-TRP may transmit theDisc-RS only if the absolute speed of the Mbl-TRP vehicle is above apre-configured threshold, e.g., 15 km/h. One of the potential benefitsof speed-dependent Disc-RS activation is to effectively prevent anStrSide-UE from being handed over to a Mbl-TRP. The proposed concept isillustrated in FIG. 4 .

Summary of UE Sending Measurement Report

FIG. 5 is a flowchart illustrating a procedure for the detection of aMbl-TRP and the triggering of a measurement report in accordance with anexemplary embodiment. For a UE connected to a Fxd-TRP or possiblyconnected to another Mbl-TRP (as shown at step 501), in step 503, the UEdetects the Disc-RS transmitted by a Mbl-TRP. Then, in step 505, the UEuses one or more of the conditions discussed above for triggering ameasurement report in the presence of Mbl-TRP, e.g., the RSRP of thedetected Disc-RS (RSRP_(Disc-RS)) being above a threshold (Th_(Disc-RS))and/or the RSRP of the detected Disc-RS becoming better than that of thecurrent cell (RSRPCurrent) to decide whether to potentially send ameasurement report. If this first condition is not satisfied in step505, the UE does not send a measurement report and remains connected tothe current cell. If, on the other hand, this first condition issatisfied in step 505, the UE proceeds to step 507, where it estimatesits speed relative to the Mbl-TRP (or possibly its absolute speed).Next, in step 509, the UE determines if the estimated speed is above orbelow a threshold speed (Th_(Speed)). If the estimated relative speed isdeemed below Th_(Speed) (thus indicating that the UE is probably onboardthe vehicle with the Mbl-TRP, i.e., is a inVeh-UE), flow proceeds tostep 511, in which the UE sends a measurement report, and, in someembodiments, the estimation of the relative speed, to the TRP of thecurrent cell. If the second condition (or set of conditions) is not met,the UE does not send measurement report and remains connected 501 to thecurrent cell.

Conditions for UE to Send Inter-Frequency Measurement Request

Embodiments for the UE to request inter-frequency measurements of aMbl-TRP operating out-of-band of the Fxd-TRP to which the UE iscurrently attached (or otherwise associated with) are provided in thissection.

As previously described, the UE may be configured to first detect thepresence of the discovery beacon signals transmitted by the Mbl-TRP onthe frequency band of the Fxd-TRP. The actual carrier frequency for theout-of-band Mbl-TRP may be pre-configured, for example, via RRC (e.g.,via dedicated signaling or over the system information), or it could beprovisioned by the network operator in the Universal Subscriber IdentityModule (USIM).

UE Detects the Presence of the Mbl-TRP by Receiving the Beacon Signals

In one embodiment, the UE may be configured to monitor the discoverybeacon signal, which may be transmitted by the Mbl-TRP on the Fxd-TRPfrequency, as discussed above. Also as previously noted, thecharacteristics of the discovery beacon signal may be configurable andthe UE may be configured to detect the presence of the discovery beaconsignal based on these signal characteristics.

Such configuration may be static, semi-static, or dynamic. For example,the network may determine that a UE is requiring many handovers in ashort period of time (possibly indicating that the UE is mobile, e.g.,an InVeh-UE). Therefore, the network may configure the UE to monitor forthe presence of Mbl-TRP beacon signals, possibly also indicatingappropriate signal characteristics to seek out.

In yet another embodiment as previously discussed, the UE also may beconfigured to monitor one or more inter-RAT signals or messages todetect the Mbl-TRP.

UE Makes Decision Whether or not to Send Inter-Frequency MeasurementRequests Based on Relative Speed

The UE may be configured to estimate its speed relative to some fixedreference points to determine whether it is a StrSide-UE or an InVeh-UE.One specific example of the fixed reference point may be the Fxd-TRP ofthe serving cell when the UE is in idle mode or the Fxd-TRP to which theUE is connected. For example, the UE may use the synchronization signalsand/or reference signals transmitted by the Fxd-TRP to estimate itsspeed relative to the Fxd-TRP. Depending on the estimated relative speedlevel, there may exist several possible scenarios as listed in Table 2.

TABLE 2 Speed level relative to Fxd-TRP Low High Scenario 3) UE is aStrSide-UE 3) UE is an InVeh-UE 4) UE is a StrSide-UE in transition to4) UE is a high- InVeh-UE and the vehicles stops on the speed UE street(e.g., bus stops, red light, traffic in other vehicle congestion andetc.)

Based on the above listed scenarios, the UE may be configured to sendthe inter-frequency measurement requests to the network if the UE'srelative speed is above a configured threshold, i.e., its relative speedis deemed “High”. Otherwise, the UE may be configured not to send theinter-frequency measurement requests. One of the benefits of thisapproach is that a StrSide-UE may avoid sending unnecessary measurementrequests and performing unnecessary inter-frequency measurements, whichmay be more efficient from the perspectives of both the signalingoverhead and the UE's energy consumption. A second advantage may bethat, for UEs getting on the vehicle (i.e., StrSide-UE in transition toInVeh-UE), it is beneficial for the UEs to stay connected to the Fxd-TRPbecause, for UEs in a low mobility state, the RSRP of the Fxd-TRP may besufficiently high for the UE to maintain a good service quality. Inpractice, the UE may be configured so that, when the RSRP of the Fxd-TRPbecomes lower at the UE, the UE sends an inter-frequency measurementrequest (such as described above) and makes the appropriate measurementsaccording to the network control, which may eventually lead the networkto configure the UE to perform a handover.

The UE may also be configured with additional conditions before it willsend an inter-frequency (or inter-RAT) measurement request, such as oneor more of the conditions discussed above for triggering a measurementreport in the presence of a Mbl-TRP. The UE may use the above relativespeed-based condition as a first condition and one or more of the otherconditions listed above as a set of second conditions. Once both thefirst and second conditions are met, the UE may send the inter-frequencymeasurement request to the network.

Handling High Speed UEs in Other Vehicles

Using the above relative speed-based criterion may not be sufficient toprevent UEs in other high speed vehicles from sending an inter-frequency(or inter-RAT) measurement request when undesirable. In other words, itmay be difficult to differentiate a “real” InVeh-UE from UEs in othervehicles based only on relative speed.

To solve this issue, one embodiment may be to configure the UE to make afirst inter-frequency measurement request. Then the UE is configuredwith a back-off timer (which may be pre-configured by the network) sothat the UE does not make another request to the same Fxd-TRP with thesame Disc-RS during the back off period. The rationale behind thisembodiment is that, for a high-speed UE in another vehicle, the measuredRSRP of the Mbl-TRP after the back off period expires may besufficiently low (e.g., because the “other” vehicle containing the UEhas moved further away from the vehicle with the Mbl-TRP) that ameasurement report would not be triggered after the back-off timerexpires (i.e., after the back off period).

Embodiments for a UE to Estimate its Speed Level Relative to a FixedReference Point

In one embodiment, the UE may be configured to estimate its relativespeed by exploiting the signal characteristics of the received referencesignals from a fixed reference point. The fixed reference point may beconveniently selected as the serving Fxd-TRP for the UE. To be morespecific, the UE may be configured to monitor the reference signalstransmitted by its serving Fxd-TRP to estimate the channel correlationat two time instances t1 and t2 with t2−t1=τ. For example, denoting thetime-domain channel estimate at a specific resource block (RB) at time tby ĥ(t), the UE may estimate the channel correlation byR(τ)=E{ĥ(t)ĥ*(t+τ)}.

The UE may be configured with a threshold A, which may be pre-configuredby the network or signaled by the network. The UE may estimate theapproximate channel coherence using the following criterion:τ_(max)=min τs.t. R(τ)≤λ.

To be more general, the UE may use one or more of the followingreference symbols transmitted by the Fxd-TRPs for the estimation of thechannel coherence time:

-   -   Cell-specific reference signal;    -   Demodulation reference signal;    -   CSI reference signal; and/or    -   Positioning reference signal.

The UE may determine its relative speed level based on the relationbetween the relative speed and the estimated channel coherence timeshown in Table 3 below.

TABLE 3 Channel coherence time Short Long Relative speed level High Low

One of the potential benefits of the above channel coherence-basedestimation approach is that the estimation may be inherently integratedinto the intra-frequency measurement or downlink signal receptionprocedure, and, therefore, no additional signaling or UE processing isrequired.

Alternately or additionally, the UE may estimate its absolute speedusing GPS signals. Since the Fxd-TRP is a fixed point, the UE's absolutespeed and relative speed to the Fxd-TRP are equivalent.

UE Configured by the Network to Perform Inter-Frequency Measurement

In a second set of approaches, the UE may be configured by the networkto enable the inter-frequency measurement. More specifically, it may bea desired feature for the next-generation cellular network, e.g., 3GPPNR, to know the network topology. For example, the network may be awareof the location of the Mbl-TRPs. The network may configure the UE viahigher layer signaling, such as RRC signaling, to monitor thesynchronization signals of a proximate Mbl-TRP, such as the Disc-RS,when the network determines that the UE has become proximate to aMbl-TRP.

IV. Conditions to Trigger Measurement for UE in Idle Mode

This section discusses embodiments for an idle-mode UE to performmeasurements and cell selection/reselection. From the UE's energyconsumption perspective, it may beneficial to limit the measurements theUE is required to perform. More specifically, the UE may be configuredwith at least one of the following measurement and/or cellselection/reselection conditions (note that the UE may either be campedon a Fxd-TRP or a Mbl-TRP):

-   -   The UE's speed relative to the Fxd-TRP with which it is        currently associated is below a pre-configured threshold;    -   The UE's speed relative to the Fxd-TRP with which it is        currently associated is greater than a pre-configured threshold;    -   The UE's speed relative to another Mbl-TRP is greater than        another pre-configured threshold;    -   Any one or more of the conditions listed above in section III.

In order to allow a UE to perform measurement of a Mbl-TRP upon thediscovery of the Mbl-TRP, a UE in idle mode but camped on a Fxd-TRP, theUE may be configured with a higher Fxd-TRP signal strength searchthreshold than when it detects another Fxd-TRP. That is, the UE may beconfigured to search and report with respect to a detected Mbl-TRP evenif the signal from the Fxd-TRP with which it is currently associated isvery strong. One of the potential benefits of this approach is that itensures that the UE searches/measures the Mbl-TRP even under goodquality of the Fxd-TRP's signal. More specifically, in the context ofthe existence of Mbl-TRPs, the fact that a UE has a strong signal fromthe Fxd-TRP that it is camped on does not necessarily mean that there isnot a Mbl-TRP in the vicinity that is more preferable (for example, inthe scenario where an idle-UE currently camped on a Fxd-TRP just got ona bus).

To save UE battery power by limiting the measurements that the UE needsto perform, in another approach, the UE may be configured to considerthe operating frequency of Mbl-TRPs to be higher priority than theoperating frequency of Fxd-TRPs. That is, the UE may be configured toalways perform a measurement when the measurement is in a frequency bandhaving higher priority than the frequency band of the TRP on which it iscamped. This approach may allow the UE to perform measurement on theMbl-TRP's frequency with a configurable periodicity.

In yet another approach, the Mbl-TRP may be configured to transmit aburst of cell reselection beacon signals on the Fxd-TRP's band to reducethe quality of the Fxd-TRP, thus triggering a search on the Mbl-TRP'sfrequency. The cell reselection beacon signals may be any signal in thefrequency band of the Fxd-TRP that would cause interference in thatband, including the discovery beacon signal.

In an alternative approach that is similar to what is discussed inSection III, the UE may be configured with a subset of first conditions.For example, for a UE in idle mode but camped on a Fxd-TRP, the UE maybe configured with the first condition(s) being that the UE's relativespeed to the Fxd-TRP is greater than a pre-configured threshold, i.e.,the UE may be an InVeh-UE. Once the first condition and one or more ofthe other conditions are met by the UE, the UE may be configured to takemeasurements on the Mbl-TRP's frequency and, if appropriate, reselect tothe Mbl-TRP. In another example, for a UE in idle mode but camped on aMbl-TRP, the UE may be configured with the first condition being thatthe UE's relative speed to the Fxd-TRP is below another pre-configuredthreshold, i.e., the UE may be a StrSide-UE. Then, similarly, if thefirst condition and one or more of the other conditions are met by theUE, the UE may be configured to take measurements on the Fxd-TRP'sfrequency and, if appropriate, reselect to the Fxd-TRP.

V. Example Embodiments

Handover Procedure from Fxd-TRP to Mbl-TRP

FIG. 6 is a signal flow diagram illustrating an exemplary process basedon one or more of the above embodiments for enabling the handing over ofa UE from a Fxd-TRP to a Mbl-TRP operating in out-of-band mode. Theexemplary process starts out with a UE 610 that is in connected mode(601) and attached to a Fxd-TRP 620. At 603, the UE detects the presenceof the Mbl-TRP based on the discovery beacon signal as previouslydescribed (such as in Section II). Next, at 605, the UE 610 determineswhether conditions are appropriate for sending an inter-frequencymeasurement request (such as described in Section III). Assuming theconditions are appropriate, at 607, the UE 610 sends an inter-frequencymeasurement request. At 609, the Fxd-TRP 620 sends a measurementconfiguration message back to the UE 610. The UE then takes theinter-frequency measurements, as shown at 611. Next, at 613, the UEdetermines if conditions are appropriate for sending a measurementreport (such as described in Section III) and, assuming so, sends theinter-frequency measurements, to the Fxd-TRP, as shown at 615. At 617,the Fxd-TRP 620 sends a handover command to the UE. Finally, at 619, theUE 610 synchronizes to and accesses the target Mbl-TRP. The process ofmaintaining the connection to the Mbl-TRP includes monitoring theMaint-RS.

The procedure illustrated in FIG. 6 is largely applicable to bothin-band Mbl-TRP and out-of-band Mbl-TRP operational scenarios. Thedifference between the two scenarios may be that, for the out-of-bandMbl-TRP scenario, the UE may perform an additional step of requestinginter-frequency measurement when the triggering conditions are met.

VI. Conclusion

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer readable medium for execution by a computeror processor. Examples of non-transitory computer-readable storage mediainclude, but are not limited to, a read only memory (ROM), random accessmemory (RAM), a register, cache memory, semiconductor memory devices,magnetic media such as internal hard disks and removable disks,magneto-optical media, and optical media such as CD-ROM disks, anddigital versatile disks (DVDs). A processor in association with softwaremay be used to implement a radio frequency transceiver for use in a WTRU102, UE, terminal, base station, RNC, or any host computer.

Moreover, in the embodiments described above, processing platforms,computing systems, controllers, and other devices containing processorsare noted. These devices may contain at least one Central ProcessingUnit (“CPU”) and memory. In accordance with the practices of personsskilled in the art of computer programming, reference to acts andsymbolic representations of operations or instructions may be performedby the various CPUs and memories. Such acts and operations orinstructions may be referred to as being “executed”, “computerexecuted”, or “CPU executed”.

One of ordinary skill in the art will appreciate that the acts andsymbolically represented operations or instructions include themanipulation of electrical signals by the CPU. An electrical systemrepresents data bits that can cause a resulting transformation orreduction of the electrical signals and the maintenance of data bits atmemory locations in a memory system to thereby reconfigure or otherwisealter the CPU's operation, as well as other processing of signals. Thememory locations where data bits are maintained are physical locationsthat have particular electrical, magnetic, optical, or organicproperties corresponding to or representative of the data bits. Itshould be understood that the exemplary embodiments are not limited tothe above-mentioned platforms or CPUs and that other platforms and CPUsmay support the provided methods.

The data bits may also be maintained on a computer readable mediumincluding magnetic disks, optical disks, and any other volatile (e.g.,Random Access Memory (“RAM”)) or non-volatile (e.g., Read-Only Memory(“ROM”)) mass storage system readable by the CPU. The computer readablemedium may include cooperating or interconnected computer readablemedium, which exist exclusively on the processing system or aredistributed among multiple interconnected processing systems that may belocal or remote to the processing system. It is understood that therepresentative embodiments are not limited to the above-mentionedmemories and that other platforms and memories may support the describedmethods.

In an illustrative embodiment, any of the operations, processes, etc.described herein may be implemented as computer-readable instructionsstored on a computer-readable medium. The computer-readable instructionsmay be executed by a processor of a mobile unit, a network element,and/or any other computing device.

There is little distinction left between hardware and softwareimplementations of aspects of systems. The use of hardware or softwareis generally (but not always, in that in certain contexts the choicebetween hardware and software may become significant) a design choicerepresenting cost vs. efficiency tradeoffs. There may be variousvehicles by which processes and/or systems and/or other technologiesdescribed herein may be effected (e.g., hardware, software, and/orfirmware), and the preferred vehicle may vary with the context in whichthe processes and/or systems and/or other technologies are deployed. Forexample, if an implementer determines that speed and accuracy areparamount, the implementer may opt for a mainly hardware and/or firmwarevehicle. If flexibility is paramount, the implementer may opt for amainly software implementation. Alternatively, the implementer may optfor some combination of hardware, software, and/or firmware.

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, or examples may be implemented,individually and/or collectively, by a wide range of hardware, software,firmware, or virtually any combination thereof. Suitable processorsinclude, by way of example, a general purpose processor, a specialpurpose processor, a conventional processor, a digital signal processor(DSP), a plurality of microprocessors, one or more microprocessors inassociation with a DSP core, a controller, a microcontroller,Application Specific Integrated Circuits (ASICs), Application SpecificStandard Products (ASSPs); Field Programmable Gate Arrays (FPGAs)circuits, any other type of integrated circuit (IC), and/or a statemachine.

Although features and elements are provided above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. The present disclosure is not to be limitedin terms of the particular embodiments described in this application,which are intended as illustrations of various aspects. Manymodifications and variations may be made without departing from itsspirit and scope, as will be apparent to those skilled in the art. Noelement, act, or instruction used in the description of the presentapplication should be construed as critical or essential to theinvention unless explicitly provided as such. Functionally equivalentmethods and apparatuses within the scope of the disclosure, in additionto those enumerated herein, will be apparent to those skilled in the artfrom the foregoing descriptions. Such modifications and variations areintended to fall within the scope of the appended claims. The presentdisclosure is to be limited only by the terms of the appended claims,along with the full scope of equivalents to which such claims areentitled. It is to be understood that this disclosure is not limited toparticular methods or systems.

It is also to be understood that the terminology used herein is for thepurpose of describing particular embodiments only, and is not intendedto be limiting. As used herein, when referred to herein, the terms“station” and its abbreviation “STA”, “user equipment” and itsabbreviation “UE” may mean (i) a wireless transmit and/or receive unit(WTRU), such as described infra; (ii) any of a number of embodiments ofa WTRU, such as described infra; (iii) a wireless-capable and/orwired-capable (e.g., tetherable) device configured with, inter alia,some or all structures and functionality of a WTRU, such as describedinfra; (iii) a wireless-capable and/or wired-capable device configuredwith less than all structures and functionality of a WTRU, such asdescribed infra; or (iv) the like. Details of an example WTRU, which maybe representative of any UE recited herein, are provided below withrespect to FIGS. 1A-1E, 2, and 3 .

In certain representative embodiments, several portions of the subjectmatter described herein may be implemented via Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs),digital signal processors (DSPs), and/or other integrated formats.However, those skilled in the art will recognize that some aspects ofthe embodiments disclosed herein, in whole or in part, may beequivalently implemented in integrated circuits, as one or more computerprograms running on one or more computers (e.g., as one or more programsrunning on one or more computer systems), as one or more programsrunning on one or more processors (e.g., as one or more programs runningon one or more microprocessors), as firmware, or as virtually anycombination thereof, and that designing the circuitry and/or writing thecode for the software and or firmware would be well within the skill ofone of skill in the art in light of this disclosure. In addition, thoseskilled in the art will appreciate that the mechanisms of the subjectmatter described herein may be distributed as a program product in avariety of forms, and that an illustrative embodiment of the subjectmatter described herein applies regardless of the particular type ofsignal bearing medium used to actually carry out the distribution.Examples of a signal bearing medium include, but are not limited to, thefollowing: a recordable type medium such as a floppy disk, a hard diskdrive, a CD, a DVD, a digital tape, a computer memory, etc., and atransmission type medium such as a digital and/or an analogcommunication medium (e.g., a fiber optic cable, a waveguide, a wiredcommunications link, a wireless communication link, etc.).

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely examples, and that in fact many other architectures may beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality may beachieved. Hence, any two components herein combined to achieve aparticular functionality may be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermediate components. Likewise, any two componentsso associated may also be viewed as being “operably connected”, or“operably coupled”, to each other to achieve the desired functionality,and any two components capable of being so associated may also be viewedas being “operably couplable” to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, where only oneitem is intended, the term “single” or similar language may be used. Asan aid to understanding, the following appended claims and/or thedescriptions herein may contain usage of the introductory phrases “atleast one” and “one or more” to introduce claim recitations. However,the use of such phrases should not be construed to imply that theintroduction of a claim recitation by the indefinite articles “a” or“an” limits any particular claim containing such introduced claimrecitation to embodiments containing only one such recitation, even whenthe same claim includes the introductory phrases “one or more” or “atleast one” and indefinite articles such as “a” or “an” (e.g., “a” and/or“an” should be interpreted to mean “at least one” or “one or more”). Thesame holds true for the use of definite articles used to introduce claimrecitations. In addition, even if a specific number of an introducedclaim recitation is explicitly recited, those skilled in the art willrecognize that such recitation should be interpreted to mean at leastthe recited number (e.g., the bare recitation of “two recitations,”without other modifiers, means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B”. Further, the terms“any of” followed by a listing of a plurality of items and/or aplurality of categories of items, as used herein, are intended toinclude “any of,” “any combination of,” “any multiple of,” and/or “anycombination of” multiples of the items and/or the categories of items,individually or in conjunction with other items and/or other categoriesof items. Moreover, as used herein, the term “set” or “group” isintended to include any number of items, including zero. Additionally,as used herein, the term “number” is intended to include any number,including zero.

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein maybe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to”, “at least”, “greater than”, “less than”, and the likeincludes the number recited and refers to ranges which can besubsequently broken down into subranges as discussed above. Finally, aswill be understood by one skilled in the art, a range includes eachindividual member. Thus, for example, a group having 1-3 cells refers togroups having 1, 2, or 3 cells. Similarly, a group having 1-5 cellsrefers to groups having 1, 2, 3, 4, or 5 cells, and so forth.

Moreover, the claims should not be read as limited to the provided orderor elements unless stated to that effect. In addition, use of the terms“means for” in any claim is intended to invoke 35 U.S.C. § 112, ¶6 ormeans-plus-function claim format, and any claim without the terms “meansfor” is not so intended.

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention.

Throughout the disclosure, one of skill understands that certainrepresentative embodiments may be used in the alternative or incombination with other representative embodiments.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer readable medium for execution by a computeror processor. Examples of non-transitory computer-readable storage mediainclude, but are not limited to, a read only memory (ROM), random accessmemory (RAM), a register, cache memory, semiconductor memory devices,magnetic media such as internal hard disks and removable disks,magneto-optical media, and optical media such as CD-ROM disks, anddigital versatile disks (DVDs). A processor in association with softwaremay be used to implement a radio frequency transceiver for use in aWRTU, UE, terminal, base station, RNC, or any host computer.

Moreover, in the embodiments described above, processing platforms,computing systems, controllers, and other devices containing processorsare noted. These devices may contain at least one Central ProcessingUnit (“CPU”) and memory. In accordance with the practices of personsskilled in the art of computer programming, reference to acts andsymbolic representations of operations or instructions may be performedby the various CPUs and memories. Such acts and operations orinstructions may be referred to as being “executed”, “computerexecuted”, or “CPU executed”.

One of ordinary skill in the art will appreciate that the acts andsymbolically represented operations or instructions include themanipulation of electrical signals by the CPU. An electrical systemrepresents data bits that can cause a resulting transformation orreduction of the electrical signals and the maintenance of data bits atmemory locations in a memory system to thereby reconfigure or otherwisealter the CPU's operation, as well as other processing of signals. Thememory locations where data bits are maintained are physical locationsthat have particular electrical, magnetic, optical, or organicproperties corresponding to or representative of the data bits.

The data bits may also be maintained on a computer readable mediumincluding magnetic disks, optical disks, and any other volatile (e.g.,Random Access Memory (“RAM”)) or non-volatile (“e.g., Read-Only Memory(“ROM”)) mass storage system readable by the CPU. The computer readablemedium may include cooperating or interconnected computer readablemedium, which exist exclusively on the processing system or aredistributed among multiple interconnected processing systems that may belocal or remote to the processing system. It is understood that therepresentative embodiments are not limited to the above-mentionedmemories and that other platforms and memories may support the describedmethods.

No element, act, or instruction used in the description of the presentapplication should be construed as critical or essential to theinvention unless explicitly described as such. In addition, as usedherein, the article “a” is intended to include one or more items. Whereonly one item is intended, the term “one” or similar language is used.Further, the terms “any of” followed by a listing of a plurality ofitems and/or a plurality of categories of items, as used herein, areintended to include “any of,” “any combination of,” “any multiple of,”and/or “any combination of” multiples of the items and/or the categoriesof items, individually or in conjunction with other items and/or othercategories of items. Further, as used herein, the term “set” is intendedto include any number of items, including zero. Further, as used herein,the term “number” is intended to include any number, including zero.

Moreover, the claims should not be read as limited to the describedorder or elements unless stated to that effect. In addition, use of theterm “means” in any claim is intended to invoke 35 U.S.C. § 112, ¶6, andany claim without the word “means” is not so intended.

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs),Application Specific Standard Products (ASSPs); Field Programmable GateArrays (FPGAs) circuits, any other type of integrated circuit (IC),and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WRTU), user equipment (UE), terminal, base station, Mobility ManagementEntity (MME) or Evolved Packet Core (EPC), or any host computer. TheWRTU may be used m conjunction with modules, implemented in hardwareand/or software including a Software Defined Radio (SDR), and othercomponents such as a camera, a video camera module, a videophone, aspeakerphone, a vibration device, a speaker, a microphone, a televisiontransceiver, a hands free headset, a keyboard, a Bluetooth® module, afrequency modulated (FM) radio unit, a Near Field Communication (NFC)Module, a liquid crystal display (LCD) display unit, an organiclight-emitting diode (OLED) display unit, a digital music player, amedia player, a video game player module, an Internet browser, and/orany Wireless Local Area Network (WLAN) or Ultra Wide Band (UWB) module.

Although the invention has been described in terms of communicationsystems, it is contemplated that the systems may be implemented insoftware on microprocessors/general purpose computers (not shown). Incertain embodiments, one or more of the functions of the variouscomponents may be implemented in software that controls ageneral-purpose computer.

In addition, although the invention is illustrated and described hereinwith reference to specific embodiments, the invention is not intended tobe limited to the details shown. Rather, various modifications may bemade in the details within the scope and range of equivalents of theclaims and without departing from the invention.

What is claimed:
 1. A method implemented in a wireless transmit receiveunit (WTRU), the method comprising: receiving a discovery referencesignal from a mobile transmission point; responsive to the discoveryreference signal and determinations that: a) a first estimated speed ofthe WTRU relative to a transmission point with which the WTRU isassociated is greater than a first threshold; and b) a first signalmeasurement of a first signal received from the transmission point isless than a second threshold, determining (i) a second estimated speedof the WTRU relative to the mobile transmission point and (ii) a secondsignal measurement of the discovery reference signal; and transmitting ameasurement report to a network responsive to determinations that: c)the second estimated speed is less than a third threshold; and d) thesecond signal measurement is greater than a fourth threshold.
 2. Themethod of claim 1, further comprising synchronizing to the mobiletransmission point.
 3. The method of claim 1, comprising: responsive tothe discovery reference signal and determinations that: a) the firstestimated speed is greater than the first threshold; and b) the firstsignal measurement is less than the second threshold, transmitting, tothe transmission point, information indicating an inter-frequencymeasurement request; receiving, from the transmission point, informationindicating a measurement configuration; and performing inter-frequencymeasurements based on the measurement configuration.
 4. The method ofclaim 1, wherein receiving the discovery reference signal comprises:detecting a discovery beacon on a first carrier, wherein the firstcarrier is the same carrier on which the WTRU will receive the firstsignal; transmitting, to the transmission point, a request for ameasurement gap; receiving, from the transmission point, informationindicating the measurement gap; and receiving the discovery referencesignal on a second carrier during the measurement gap.
 5. The method ofclaim 1, further comprising: determining that the discovery referencesignal is from the mobile transmission point based on signalcharacteristics of the discovery reference signal, wherein the signalcharacteristics comprise at least one of: a timing offset between thediscovery reference signal and a frame timing at which discoveryreference signals are received; a periodicity of the discovery referencesignal; a set of physical resource blocks over which the discoveryreference signal is received; a frequency over which the discoveryreference signal is received; a beam parameter of the discoveryreference signal; a synchronization signal block associated with thediscovery reference signal; a signal sequence type of the discoveryreference signal; and a sequence parameter of the discovery referencesignal.
 6. The method of claim 1, wherein: determining the firstestimated speed comprises at least one of: estimating a speed of theWTRU relative to a fixed reference point using a global positioningsystem; and estimating channel correlation with respect to referencesignals received from the transmission point at two time instances; anddetermining the second estimated speed comprises at least one of:estimating a channel coherence time using signal characteristics of thediscovery reference signal; determining a level of consistency betweenmultiple reference-signal-received-power measurements of the mobiletransmission point; and using information obtained from avehicle-to-vehicle message or a vehicle-to-infrastructure messagereceived by the WTRU, wherein the information indicates at least one ofan identification of a vehicle with which the mobile transmission pointis associated, a speed of the vehicle, a direction of the vehicle, andlocation of the vehicle.
 7. The method of claim 1, further comprisingsynchronizing to the mobile transmission point using the discoveryreference signal or a maintenance reference signal received from themobile transmission point.
 8. The method of claim 1, further comprising:receiving from the mobile transmission point a maintenance referencesignal, wherein the maintenance reference signal has signalcharacteristics different from the signal characteristics of thediscovery reference signal; and using the maintenance reference signalto maintain connection with the mobile transmission point.
 9. The methodof claim 1, wherein the measurement report comprises informationindicating the second signal measurement.
 10. The method of claim 1,wherein the second signal measurement comprises at least one of a signalstrength of the mobile transmission point and a signal quality of themobile transmission point, including any of: a reference signal receivedpower of the mobile transmission point; and a plurality ofreference-signal-received-power measurements of the mobile transmissionpoint.
 11. A wireless transmit receive unit (WTRU) comprising circuitry,including a transmitter, receiver and a processor, configured to:receive a discovery reference signal from a mobile transmission point;responsive to the discovery reference signal and determinations that: a)a first estimated speed of the WTRU relative to a transmission pointwith which the WTRU is associated is greater than a first threshold; andb) a first signal measurement of a first signal received from thetransmission point is less than a second threshold, determine (i) asecond estimated speed of the WTRU relative to the mobile transmissionpoint and (ii) a second signal measurement of the discovery referencesignal; and transmit a measurement report to a network responsive todeterminations that: c) the second estimated speed is less than a thirdthreshold; and d) the second signal measurement is greater than a fourththreshold.
 12. The WTRU of claim 11, wherein the circuitry is furtherconfigured to synchronize to the mobile transmission point.
 13. The WTRUof claim 11, wherein the circuitry is configured to: responsive to thediscovery reference signal and determinations that: a) the firstestimated speed is associated is greater than the first threshold; andb) the first signal measurement is less than the second threshold,transmit, to the transmission point, information indicating aninter-frequency measurement request; receive, from the transmissionpoint, information indicating a measurement configuration; and performinter-frequency measurements based on the measurement configuration. 14.The WTRU of claim 11, wherein the circuitry being configured to receivethe discovery reference signal comprises the circuitry being configuredto: detect a discovery beacon on a first carrier, wherein the firstcarrier is the same carrier on which the WTRU will receive the firstsignal; transmit, to the transmission point, a request for a measurementgap; receive, from the transmission point, information indicating themeasurement gap; and receive the discovery reference signal on a secondcarrier during the measurement gap.
 15. The WTRU of claim 11, whereinthe circuitry is configured to: determine that the discovery referencesignal is from the mobile transmission point based on signalcharacteristics of the discovery reference signal, wherein the signalcharacteristics comprise at least one of: a timing offset between thediscovery reference signal and a frame timing at which discoveryreference signals are received; a periodicity of the discovery referencesignal; a set of physical resource blocks over which the discoveryreference signal is received; a frequency over which the discoveryreference signal is received; a beam parameter of the discoveryreference signal; a synchronization signal block associated with thediscovery reference signal; a signal sequence type of the discoveryreference signal; and a sequence parameter of the discovery referencesignal.
 16. The WTRU of claim 11, wherein: the circuitry beingconfigured to determine the first estimated speed comprises at least oneof: the circuitry being configured to estimate a speed of the WTRUrelative to a fixed reference point using a global positioning system;and the circuitry being configured to estimate channel correlation withrespect to reference signals received from the transmission point at twotime instances; and the circuitry being configured to determine thesecond estimated speed comprises at least one of: the circuitry beingconfigured to estimate a channel coherence time using signalcharacteristics of the discovery reference signal; the circuitry beingconfigured to determine a level of consistency between multiplereference-signal-received-power measurements of the mobile transmissionpoint; and the circuitry being configured to use information obtainedfrom a vehicle-to-vehicle message or a vehicle-to-infrastructure messagereceived by the WTRU, wherein the information indicates at least one ofan identification of a vehicle with which the mobile transmission pointis associated, a speed of the vehicle, a direction of the vehicle, andlocation of the vehicle.
 17. The WTRU of claim 11, wherein the circuitryis configured to synchronize to the mobile transmission point using thediscovery reference signal or a maintenance reference signal receivedfrom the mobile transmission point.
 18. The method of claim 11, whereinthe circuitry is configured to: receive from the mobile transmissionpoint a maintenance reference signal, wherein the maintenance referencesignal has signal characteristics different from the signalcharacteristics of the discovery reference signal; and use themaintenance reference signal to maintain connection with the mobiletransmission point.
 19. The WTRU of claim 11, wherein the measurementreport comprises information indicating the second signal measurement.20. The WTRU of claim 11, wherein the second signal measurementcomprises at least one of a signal strength of the mobile transmissionpoint and a signal quality of the mobile transmission point, includingany of: a reference signal received power of the mobile transmissionpoint; and a plurality of reference-signal-received-power measurementsof the mobile transmission point.